Mixed-species versus monocultures in plantation forestry: Development, benefits, ecosystem services and perspectives for the future

TLDR

Plantation forests are expanding to curb deforestation and supply goods and services, yet monocultures dominate; growing climate pressures and resource limits have spurred interest in mixed-species and agroforestry, though few studies confirm successful mixtures and research continues to explore their benefits. The study reviews the evolution of monoculture and mixed-species plantations, compares their pros, cons, and ecosystem impacts, and examines species combinations with complementary traits to optimize resource use and growth. The authors analyze species mixtures by selecting complementary traits to maximize positive interactions and minimize negatives, employing advanced molecular genetics to guide species combinations. Careful design and management enable mixed-species plantations of two to four species to outperform monocultures in productivity, biodiversity, economy, and forest health.

Abstract

Plantation forests are increasing rapidly in the world in order to alleviate deforestation and degradation of natural forests, along with providing various goods and services. While monoculture plantations have been the dominant type of plantation in practice and well-recorded in research, in the face of intensifying climate change and resource scarcity, there is a growing interest in mixed-species plantations. Agroforestry systems are also catching the attention of foresters, smallholders and landowners. However, there are relatively limited number of studies on successful species mixtures. This paper first reviews the progression of monocultures and mixed-species, followed by the comparisons of advantages, disadvantages and effects on the surrounding natural ecosystems between these two types of plantations. The paper further investigates combinations of species with complementary traits for efficient use of limiting resources associated with improvement in growth development and production of tree species, as well as examining some other challenges in mixed-species. In addition, it is helpful to select and combine tree/crop species in mixtures based on complementary traits that maximise positive and minimise negative interactions and using the advance molecular technologies for genetic analysis. With careful design and proper management, mixed-species plantations with two, three or four species can be more productive and have more advantages in biodiversity, economy and forest health over monocultures. Many researchers are still working on different projects to explore the potential benefits and to promote the applications of mixed-species plantations and agroforestry.